1. Field of the Invention
The invention generally relates to a secondary optical element and a light source module, and more particularly to a secondary optical element with uniform illumination and a light source module applying the secondary optical element.
2. Description of Related Art
Due to advantages such as fast response, small volume, low power consumption and waste, high reliability, and fit for mass production, the light emitting diode (LED) has been widely applied in such fields as illumination and backlight source. In LED illumination, the LED emits a Lambertian emission pattern; this type of emission pattern exhibits an uneven illumination on the target illumination plane. When extremely high luminance or luminance contrast exists within the field of view of human vision, discomfort may be generated by the human eyes. Therefore, an important focus area is in reducing glare and improving illumination uniformity.
In conventional techniques, illumination equipments used to reduce glare include the side-lit panel light and the traditional grille lamp, which utilizes light guide design or reflector design to control the light emission pattern and to eliminate the high luminance or luminance contrast within the field of vision. However, these equipments have low light extraction efficiency. Accordingly, how to reduce glare and improve illumination uniformity while obtaining high light extraction efficiency is an important topic of research and development.